.if 1 .tm 1
.if 0 .tm 0 (error)
.if !0 .tm !0
.if -1 .tm -1 (error)
.if 1/0 .tm 1/0 (error)
.if 1%2 .tm 1%2
ACCEPT ELSE PART
.ie !t \{\
Level 1, if part, reject
.\}
.el \{\
Level 1, else part, accept
.\}
ACCEPT IF PART
.ie t \{\
Level 1, if part, accept
.\}
.el \{\
Level 1, else part, reject
.\}
ACCEPT IF (level 1) and ELSE (level 2)
.ie t \{\
Level 1, if part, accept
.ie n \{\
Level 2, if part, reject
.\}
.el \{\
Level 2, else part, accept
.\}
.el \{\
Level 1, else part, reject
.\}
.\}
